Thanks for the update. Lagon does not have any fuming action. I think you are thinking of Lorsban, which is not registered on soys and is incredibly detrimentl to the natural enemies that are trying to help. No, I don’t think it is too late to apply Matador or Silencer. If the aphids are closer to the 500 per plant range and you have a deep canopy, you may want to bump up the rate of Matador but most times we still see good success with the low rate. The key is to properly apply the product. To spray for soybean aphids you should set up the nozzles to get a MEDIUM droplet size. Use high water volumes (20 GPA) and high pressures (70 psi), while targeting the spray at the middle of the canopy (not the top as you would for spraying other things). If we see control issues, it is usually due to poor application.